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jbdbd
cellulose R values

I would like to blow cellulose into the wall cavities of my 1908 home. from what i can tell filling a 3.5 in. bay will get me to about R13. I want to get closer to R19. My framing is actual
2x4 which will get me a little more, but i fear very little.
does cellulose behave like fiberglass? if compacted does its R value decrease?
I imagine that this is an issue that folks that do blown in for a living encounter all the time and i wonder how its dealt with.
i'd love any input,
thanks

pomer
Re: cellulose R values

i'm in the same vote but i'am learning retro spray foam seams to be a better way a little more but they say it won't settle

canuk
Re: cellulose R values

The R value of cellulose is rated at it's settled density.

Check these links for more information : http://www.cellulose.org/pdf/cellulose_benefits/cons_report4.pdf

http://www.cellulose.org/pdf/cellulose_benefits/cons-report-1.pdf

Hope this helps.:)

goldhiller
Re: cellulose R values

does cellulose behave like fiberglass?

No... thankfully. FG loses R-value as the temp differential increases. R-value is rated in a lab at a given delta-T. As that delta-T increases, the R-values of various insulation materials perform vastly different. Cells outperforms FG by a wide margin.

if compacted does its R value decrease?

No, it increases. That's one reason why it's important to have it properly installed in walls.(high density packing/blowing). The other reason is that properly installed high-dense ....won't settle requiring a re-blow down the road. Get it done right by an experienced installer or learn how yourself if this is gonna be DIYed. Basically,it's a matter of having a strong blower and leaning out cells to air mix. Takes longer to fill the wall that way, but the end result is far superior.

And the tighter it's packed in there, the better it seals any little holes/air leaks thereby eliminating air movement within or thru the wall. Try that with FG batts.

Also...there are no convection currents within properly installed cells..like there is inside an FG batt.

Enough of my ramblings. :)

You can Google your way to much info if you're interested. Here's one source that states many of the advantages without getting all technical and causing your brain to glaze over.

http://www.houleinsulation.com/cellulose_vs_fiberglass.html

Re: cellulose R values

We are building a new house and my husband (who's in the heating and cooling business) won't let us put anything but celulose (NuWool http://www.nuwool.com/) in our house. He's seen it many times on the job site and is amazed at how thorough they are at sealing up the house. We are putting in geothermal for our heating and cooling. He says with the two combined, our electric bill should only be around $75 a month verses the $150 to $200 we pay now.

It's also mold, mildew, and pest resistant. It shouldn't settle if it's put in correctly. It's safer also. I watched a video on how it burns compared to houses insullated with fiberglass or no insullation and it's amazing. Go to http://www.greenfiber.com/homeowners/ and click on the Big Burn Video. It's very informative.

Hope this helps.

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